The present invention relates generally to an expansible anchor, and more particularly to an expansible anchor for use in an anchoring hole of a support structure, such as a wall or the like.
Expansible anchors of this general type are well known in the art, and usually have a bolt which extends partly into and partly out of a bore hole and is provided with an engaging portion that can engage any expander member. The bolt is surrounded by an expansion sleeve and when a nut is threaded onto the outer portion of the bolt and moves into abutment with the wall in which the bore hole is formed, it draws the bolt and the expander member outwardly while holding the expansion sleeve in the bore hole, so that the expander member enters into the expansion sleeve and expands the same radially.
These prior-art constructions have certain disadvantages which makes them ill suited for some applications. In particular, the shaft of the bolt which extends out of the bore hole and onto which the nut is threaded, and which also carries an object that is to be secured to the support structure has a relatively small diameter, necessarily smaller than that of the expansion sleeve. This means that this shaft which is relatively weak must be able to withstand the entire bending and shear forces which develop when an object is fixed by means of the expansion anchor to the support structure. In addition, however, the prior-art constructions do not make it possible to simply place the object to be mounted onto the support structure so that a hole in the object registers with the bore in the support structure, or so that both the hole and the bore may even be formed simultaneously, whereupon the expansion sleeve can be introduced and secured. This is very desirable, because it greatly facilitates and speeds up the mounting operation, thus representing a saving in labor cost. The prior-art constructions, however, require that the expansion anchor can be introduced into the bore hole and anchored therein before the object to be mounted can be placed onto the support structure and secured to the bolt of the expansion anchor. This, therefore, requires a larger number of manipulative steps and increases the time required for the mounting operation and, consequently, the labor expenses.
Furthermore, it is known that in the expansion anchors of the prior art the nut which actually effects the outward movement of the bolt and hence the entry of the expander member into the expansion sleeve, must be able to abut the outer surface of the support structure. However, in certain circumstances, for instance if soft and compressible panels of insulating material are provided on the outer surface of the support structure, there is not sufficient resistance to the engagement of the nut to permit the proper expansion of the sleeve, unless the yieldable material is destroyed in the reregion of the bore hole so that the nut can then be threaded against the harder and more resistant material of the support structure itself. This is self-evidently disadvantageous in many respects.